Lens structures for optical devices, such as cameras, consist of multiple lens elements assembled in a single barrel or stacked in a wafer form, utilizing spacers, to create fixed focus lens assemblies. These lens structures have a fixed focal plane and are mechanically moved to focus on objects that are located at varying distances from the camera system.
A wafer level camera module includes a CMOS sensor, normally packaged in a Chip Scale Package (CSP), and a wafer level lens structure, having multiple replicated lenses on glass substrates. In such a configuration, no electrical connection is required between these parts.
Tunable liquid crystal lenses (TLCL) having a flat layered construction are described in PCT International Patent Application Publications no. WO 2007/098602, published on Sep. 7, 2007, WO/2009/146529 and WO/2009/146530, published on 10 Dec. 2009, and WO/2010/022503, published on 4 Mar. 2010, the specifications of which are hereby incorporated by reference as if fully set forth herein.
In U.S. Provisional Patent Application Ser. No. 61/175,025, which was filed May 3, 2009 and the substance of which is incorporated herein by reference, there is disclosed a wafer level camera with an active optical element positioned within a lens stack of the lens assembly. By applying a required electrical signal to the active element, it is possible to modify an optical property of the lens assembly without any mechanical movement. In the case of a TLCL as the active optical element, the focal plane of the lens structure can be moved, thus creating a variable focus device. With appropriate feedback such a variable focus device can be used to provide auto focus without mechanical movement.
When a wafer level camera includes an active optics element, such as a TLCL, one or more electrical connections are required to provide at least one electrical contact between the active optics element and the camera substrate (electronics), such as a Chip Scale Package or a sensor on a Printed Circuit Board (PCB). In U.S. Provisional Patent Application Ser. No. 61/175,025, which is incorporated herein by reference, this requirement is met by an integrated electrical connection structure that is provided to enable electrical contacts as part of the lens barrel assembly. At least one electrical contact provides an electrically conductive path between an outer surface of the lens mounting structure and the active optical element. The contact can be a stamped metallic piece (lead) with an incorporated spring element to ensure reliable electrical connection to a contact on a receiving device to which the lens apparatus is mounted. Alternatively, a Molded Interconnect Device (MID), used in place of lead frames in the device, can be used to create a connection between the active optical element and the camera housing or surrounding devices, in which case connection to the embedded active optical element can be achieved by means of conductive adhesives.